North Shore Connector Project

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The Challenge

Extend Port Authority’s Light Rail Transit to North Shore by 1.2 miles
Utilize twin-bored tunnels transitioning to elevated alignment
Support revitalization efforts and facilitate further transit extensions

The North Shore Connector project extended the Port Authority of Allegheny County’s Light Rail Transit system 1.2 miles from the Gateway Subway Station located in downtown Pittsburgh to the North Shore. While remaining underground in twin-bored tunnels along the North Shore, the alignment would transition to an elevated alignment before terminating near the West End Bridge. The project supported the effort to revitalize downtown Pittsburgh and the North Shore’s residential areas, business districts, educational institutions, and entertainment developments.

The Connector enabled the Port Authority to construct extensions of the transit system to other destinations within Allegheny County. With many historical buildings and elevated highway bents located along the alignment of the project, care needed to be taken to assess that they were not affected by construction activities.

The Solution

Geocomp deployed its iSite® data logging system along with the iSiteCentral® web-based data management program to deliver data to the engineers on a real time basis, 24/7. Over two weekends, the existing supports under the SR 65 North and South approaches to Ft. Duquesne Bridge were cut away, allowing the load transfer of the highway structures above to new foundation elements. The old foundations had to be removed to make room for the new light rail tunnels. Geocomp engineers and technicians were on-site for 24-hour shifts monitoring the piers while the load was transferred using a complex post-tensioning process.

Any movement greater than 6 mm triggered an alarm and work was immediately halted. The measured movements were less than 3 mm, and the work proceeded without incident.